When settng the velocty for the flatline:
By starting way to low you will see when the "flatline" (mangus) effect occurs. Your shots will start out looking like a regular barrel shot. Then when you hit on the correct velocity, suddenly the shost will not longer drop and they will appear to "float" Its really fun to see. You will notice a marked differance in the distance that the ball travels. This is something that need to be done outside. There isn't enough room to do this at an indoor shooting range.

The flat line does not suffer from the "dip" that the appex has.